Pre amp location - does it not give benefit if it is not next to aerial?

[GlynH]

In my humble opinion using the shortest length of the best coax money can buy, using the proper plugs for that cable and paying careful attention to the preparing, soldering, assembling, connecting, waterproofing the joints & running the cable is the biggest single improvement you can make and is far preferable to just sticking a pre-amplifier in-line.

Not quite sure about the earlier definition about amplifying loss on the cable(?) but obviously you cannot amplify a signal that is not there in the first place! ;^)

Although the preamp will probably have narrow bandpass filters on board by definition it cannot differentiate between noise, rfi, signal etc. and so just amplifies everything!

Terry, if you read this can you just share your experience on replacing your original coax with Westflex 103 and the proper connectors?

I know you run a masthead preamplifier (on the original cable also) but yours is a great example of what can be gained by just changing the cable.

I believe your MyFlights roughly doubled? This with just a coax change!

I have had a 1m length of W103 with the proper plugs (£6 each) pre-installed arrive today so intend to fit my Kuhne masthead preamplifier - it is a lot of work to drop my antenna array and it would be much easier to just stick the Kuhne in-line in the loft but it is not called a masthead preamplifier for nothing!

This all assumes you have a good antenna properly mounted and are using the correct preamplifier for your chosen frequency band of course...:-)

Kind regards,
-=Glyn=-

[Terry]

Hi Glyn,
           Yes i replaced the co-axial cable from the pre-amp to the bias tee with Westflex 103 and its an incredible difference over the thin stuff,before i was getting 300-400 A/C on my flights,now my highest number is 689,but its usually around 450-510,plus i`ve pulled in 4 contacts at 297.8nm and i had to re-set the polar diagram as i was a bit dubious on the distance,which was duplicated on the 2nd polar diagram,i have re-set again today and await to see if it will triplicate this.I run 1mtr lead of 103 from the antenna to the pre-amp which is sited just under the ground planes of the antenna,6mtr of 103 from the pre-amp to the bias tee,2ft of thin cable from the bias tee to the RB(this i wiil shortly change to 103).As Glyn rightly says if possible use the best co-axial cable and i think vital,the very best connectors you can afford(i know its expensive but gold plated are superb),and make sure the co-axial is PROPERLY cut,soldered,tight fitting and there`s not a whisker of outer braid anywhere exposed which would or could give a cross contact,at these frequencies even the smallest loss gives a significant reduction in reception.

     Regards Terry.

[Jeremy]

Terry,
Your attention to detail is creditable but believe me, changing a 2 ft patch lead will not make any decernable difference, assuming connections are good and that the impedence of the cable is 50 Ohms.

For interest I have an outside antenna mounted on the chimney on a bungalow so the aerial is at about 20ft. I run 10m of 103 and then 2m of small coax to the RB. I am surrounded by trees and not particularly in the clear or high up. I can 'see' 100NM radius, have 100-150 flights on My Flights @ 400 Msg/Sec (80).  What does the number in brackets mean?
How am I doing??
Jeremy

[gzerovti]

Hi,

AirNav told me via email that the number in the brackets is:

its just a way they are processed. The messages are compatcted together for better processing, i.e a lot of messages don't contain usefull data or the same data again.


Terry

[Terry]

Hi Jeremy,
                Sorry i`ve took so long to answer you but i`ve been at Glyns helping him to put a pre-amp on his antenna array.Yes,you are doing a fine job from your location and i take your point on the 2ft patch lead,but i`ll give it a try just to satisfy my curiosity as i used to use 934mhz radio some years ago and found through trials that every little bit helps at the microwave end of the spectrum.

                      Best Regards Terry.